replace existing content in file rather than using spew_utf8

.github/workflows/linux.yml

@@ -34,7 +34,7 @@ jobs:
       CIP_TAG: ${{ matrix.cip_tag }}
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
 
       - name: Bootstrap CIP
         run: |
@@ -47,7 +47,7 @@ jobs:
           cip cache-key
 
       - name: Cache CPAN modules
-        uses: actions/cache@v2
+        uses: actions/cache@v4
         with:
           path: ~/.cip
           key: ${{ runner.os }}-build-${{ steps.cache-key.outputs.key }}

Changes

@@ -1,6 +1,12 @@
 Revision history for {{$dist->name}}
 
 {{$NEXT}}
+  - The update_file method will replace the content in an existing file
+    rather than creating a new one.  A backup of the original file is
+    made while the new content is being written, in the unlikely event
+    of an error during content replacement.  The backup will be removed
+    if the replacement succeeds.  A new file will be created if one does
+    not exist, as before.  (gh#6)
 
 0.04      2024-12-15 20:35:06 -0700
   - I somehow forgot how to write POD and had to fix some (gh#5)

lib/Data/Section/Writer.pm

@@ -42,6 +42,7 @@ The name of the Perl source file.  If not provided then the source for the calle
   use Class::Tiny qw( perl_filename _files _same _formats );
   use Ref::Util qw( is_coderef is_blessed_ref is_plain_arrayref );
   use MIME::Base64 qw(encode_base64);
+  use File::Temp ();
 
   sub BUILD ($self, $) {
 
@@ -161,8 +162,19 @@ Starting with version 0.02, this method will not write to the file if the conten
       $self->_same(0);
     }
 
-    # re-write the perl with the
-    $self->perl_filename->spew_utf8($perl);
+    if(-f $self->perl_filename) {
+      use autodie qw( truncate close );
+      # re-write the perl to the file, using the existing inode
+      my $backup = Path::Tiny->new(File::Temp::tempnam($self->perl_filename->parent, $self->perl_filename->basename));
+      $self->perl_filename->copy($backup) if -f $self->perl_filename;
+      my $fh = $self->perl_filename->openrw_utf8;
+      truncate $fh, 0;
+      print $fh $perl or die "unable to write to @{[ $self->perl_filename ]} $!";
+      close $fh;
+      $backup->remove if -f $backup;
+    } else {
+      $self->perl_filename->spew_utf8($perl);
+    }
 
     return $self;
   }